The desire to improve the aesthetic characteristics of sheet-type or web-type consumer products by both embossing and printing the product is very old. (See U.S. Pat. No. 680,533 issued to Marinier et al. on Aug. 13, 1901.) Of course, much technical development has occurred in these fields in subsequent years. However, there has remained a difficulty of obtaining registered print and embossed images on stretchable substrates due to the fact that the printing process is generally a 2-dimensional application of ink or other substance onto the surface of the web of sheet product and the embossing process is generally a 3-dimensional, deformation of the sheet or web. The 3-dimensional deformation of the web results in a change in the physical dimensions, of length and width, of the web. Therefore, the printing image and the embossed image are disposed onto the substrate at different relative location on the web. This results in a misregistration of the two images which has led to a reluctance by manufacturers to produce products with highly registered print and emboss graphics.
This problem is compounded on manufacturing lines which process continuous webs of product substrate. The printing and embossing of continuous webs generally utilize rotary cylinder print and emboss rolls. Very often these rolls are on units manufactured by different companies and have different physical dimensions and drive mechanisms. Additional deviations in register can develop if the thickness, moisture content, or other parameter which impacts the stretch characteristics of the substrate change during the production run. An uncorrected process will compound the misregistration with each revolution, resulting in a “creep” of one image away from its desired position with respect to the other image.
Even print and emboss processes that utilize a single carrier/impression roller upon which the substrate is supported while being printed and embosses, as represented in European Patent Application EP 1 304 215, does not account for the change in the substrate dimensions to achieve a highly registered result.
Applicants have developed a process which automatically coordinates the actual application of the print and emboss images by the respective applicator rolls such that the print and emboss images remain in a highly registered state throughout the production of the web product.